Means for defibrating and grinding paper pulp and other vegetable fibrous material



April 24, 1956 c. LAVISTE 2,742,825

MEANS FOR DEFIBRATING AND GRINDING PAPER PULP AND OTHER VEGETABLE FIBROUS MATERIAL Filed May 27, 1954 4 Sheets-Sheet l W I I 11111 Q\ A H "q \?III/IIIIIIII III III] INVENTOR m J J0 WETQYA'ES Apnl 24, 1956 c. LAVlSTE 2,742,825

MEANS FOR DEFIBRATING AND GRINDING PAPER PULP AND OTHER VEGETABLE FIBROUS MATERIAL, Filed May 27, 1954 4 Sheets-Sheet 2 INVENTOR Aprll 24, 1956 c. LAVISTE 2,742,825

MEANS FOR DEFIBRATING AND GRINDING PAPER PULP AND OTHER VEGETABLE FIBROUS MATERIAL Filed May 27. 1954 4 Sheets-Sheet 3 I N VEN TOR 464M, (m zguzw Y PJM ATTORNEYs Ill/ll III/Ill] I I II United States Patent MEANS FOR DEFIBRATING AND GRINDING PAPER PULP AND OTHER VEGETABLE FIBROUS MATERIAL Cornelius Laviste, Pointe an Pic, Quebec, Canada Application May 27, 1954, Serial No. 432,844 16 Claims. (CI; 92-26) The present invention relates to means for defibrating and grinding paper pulp or other vegetable fibrous material and comprises a container provided with inlet and outlet for the pulp, at least two rotating defibrating and grinding The device, according to the invention, makes it possible to defibrate any vegetable fibrous material and to grind pulp at any concentration, low or high, and to obtain an excellent defibrating and grinding effect by a single passage through the device. Other advantages will appear from the following description:

The embodiments of the invention and some examples of different constructions of device are illustrated in the accompanying drawings. i

In the drawings:

Fig. l is a vertical section of one device according to the invention;

Fig. 2 is a vertical section of another device according to the invention;

Fig. 3 is a vertical section of a third device according to the invention; v I

Fig. 4 shows certain special features of the defibrating and grinding members; and

Figs. 5-7 show examples of different arrangements of knives in the defibrating and grinding members.

In the embodiment shown in Fig. 1, a rotating conical knife-disc 1, a non-rotating conical knife-disc '2 having dual working faces, and a rotating conical knife-' disc 3 are used, said discs being located in a container 4 provided with an inlet 5 and an outlet 6 for the pulp. Discs 1, 2 and 3 are'positioned across the passage between inlet 5 and outlet 6. The knife-disc 1 is secured to a rotating shaft 7 and the knife-disc 3 is secured to a rotating shaft 8, while the non-rotating knife-disc 2is secured to Each of the knife discs 1, 2, and 3, which preferably are made by casting, is formed by a knife system I 9 extending from theedge portion of the disc approxi the container.

mately to its center, so that the whole or practically the Whole surface of the disc elfectively participates in the treatment of the pulp. The knife system is arranged in such a manner that all of the knives 14 in the discs have a defibrating and grinding action. To increase the rigidity of the discs the knives are held together with connecting members 10 on the edge portion of the knives or the periphery of the disc and if necessary connecting members can be placed in suitable locations between 'the'knives to make the discs morerigid and toavoid vibration of the knives. To avoid uneven wearing of the discs the connecting members are not extended ,to the working faces of the discs. Between the individual knives 9 there are provided through openings 11 for the passage of the pulp.

between the rotating and non-rotating knife discs.

The knives may be arranged in the same manner in all the three discs or the knife system of one or all the three discs may be arranged according to different designs. The thickness of the knives as well as the width of the openings 11 may vary in accordance with the nature of the pulp to be treated and the quality of the paper to be produced.

Heavy constituents which. deposit on the bottom of the container or which are separated from the pulp due to difference of specific gravity, can easily be removed through openings 12 and 13.

Shaft 7 with the rotating knife-disc 1 and the shaft 8 with the rotating knife-disc 3 are displaceable in a known manner by means of two adjusting devices for controlling the grinding pressure between the rotating knife-discs 1 and 3 and the dual faced non-rotating knife-disc 2.

'I hetwo shafts 7 and 8 rotate preferably in opposite directions. The knife-disc 3 secured to the shaft 8 rotates at a speed substantially higher than the knife-disc 1 secured to shaft 7. The rotating speeds of discs 1 and 3 can be the same, but in that case the diameter of disc 3 is substantially larger than the diameter of knife-disc 1. The knife-disc 3 has a higher circumferential speed than knife-disc 1.

The pulp is introduced by virtue of its own weight or by a known conveying device in inlet 5 and forces itself and is forced by the higher circumferential speed of knifedisc 3 through the rotating knife-disc 1, the non-rotating dual faced knife-disc 2 and through the openings of the rotating knife-disc 3 to the outlet 6 where it leaves the apparatus in ready-ground condition. For certain pulp treatment where the pulp is introduced in the apparatus by hydraulic or steam pressure sufficient to force the pulp through the rotating knife-disc 3, the rotating knife discs 1 and 3 could rotate at the same circumferential speed but preferably in different directions. v

As shown in the drawings, shafts 7 and 8 are horiozntal, but they may also be vertically arranged.

The embodiment shown in Fig. 2 differs from the device according to Fig. l substantially therein that the rotating knife-discs are secured to the same shaft 16. The discs are rotated at the same speed and in the same direction. The shaft is not displaceable in axial direction. The rotating knife-discs 17, close to the pulp inlet, has a lower circumferential speed than has rotating knife-disc 20, close to the pulp outlet, due to the larger diameter of knifedisc-Zt). The non-rotating dual faced knife-disc is divided into two cooperating parts, Hand 19. Each part of the non-rotating dual faced knife-disc is displaceable in the axial direction to provide the necessary grinding pressure The non-rotating defibrating and grinding members are not secured directly to the cotainer as in device shown in Fig. 1, but rather are held in desired position on sliding shells 15 inside the container and are moved in axial direction by a known worm gear and rod combination-28, Fig. 3- operated from the; outside of the container. Instead of two driving motors needed for the embodiment according to 1, the embodiment shown in Fig. 2 needs only one driving motor. I

Fig. 3 shows another example of the device according to the invention, which differs from the devices according to Fig. 1 and Fig. 2 substantially therein that the rotating grinding and defibrating area without increasing the diameter of the member. The rotating knife-members 22 and 24 are'secured to the same shaft 21 and are rotatable in the'samedirection and atthe same speed. The nonrotating knife-members 23 and 25 cooperate with thev 3 rotating knife-members in a different way than shown in Fig. 1 and Fig. 2. The pulp flows through the centrally located inlet 26, is directed to the through-passage openings of the rotating knife-member 22, is defibrated and ground between the knives of the rotating and nonrotating knife-members and is forced through the throughpassage openings of the non-rotating knifemember 23 by centrifugal force developed by the rotating knife-member 22. There is a free space between the non-rotating knife-member 23 and the rotating knife-member 24 where the pulp is mixed and homogenized due to the rotating action of the rotating knife-member 24 before the pulp is directed by the said member to the throughpassage openings, is ground between the knives of the rotating knife-member 24 and non-rotating knife-member 25, and the pulp leaves the grinding zone by throughpassage openings of knife-member 25, forced by centrifugal force developed by the rotation of knifenncmber 24. The non-rotating knife-members 23 and 25 are axially displnceable and are held in desired position on sliding shells 1S inside the container and are moved in axial direction by a known worm gear and rod combination 28 operated from the outside of the container.

Fig. 4 shows some special features of the defibrating and grinding members. To avoid uneven wearing of all the parts of the working surface of the defibrating and grinding members only the knives extend to the working face. The connecting members 10 shown in Fig. 4 are placed on the edge portion of the knives or the periphery of the defibrating and grinding member, to increase the rigidity of the grinding member and to avoid vibration of the knives. If necessary, connecting members could be placed in any other place between the knives, especially when the grinding members are larger or the connecting members are needed for a different design of grinding member. As the connecting members at the circumference of a knife-disc do not extend to the working face, and to avoid the flow of the pulp outwardly from the edge portion of the knives due to centrifugal force,

defibrating and less grinding is desired such pulp re-circulation is very helpful, but when more grinding and less defibrating is needed, such recirculation can be avoided with seal plate 27.

Figs. 5-7 show some examples of different arrangements of knives in the defibrating and grinding members.

The knives can be arranged in radial direction, as shown in Figs. 5 and 7, or have an inclination in either direction. The pattern of knives, as also shown in Figs. 5 and 7, can be identical over the entire surface of the defibrating and grinding members; or the surface can be divided into sectors and each sector can have a pattern of its own, as shown in Fig. 6. The need for so many patterns depends on the special pulp treatment needed for special paper products. The working face of the knives can be smooth or grooved longitudinally or diagonally. In places Where the knives are joined together in a special pattern, the contact is made with a connecting member leaving a free space close to the joint on the working face of the defibrating and grinding member. This free space is needed for pulp circulation and forms a grinding edge on the joint to avoid uneven wearing of the defibrating and grinding member.

With the invention, it has been kept in mind that paper pulp and other vegetable fibrous materials have always to be defibrated and ground in aqueous suspension.- Water is needed to transport and to carry fibers, and water is needed to soften the fibers and the liaison between the fibers. Without water there is no defibrating and grinding possible; at least the product would not be suitable to form a sheet of paper or board. Contrary to paper pulp grinders, grinders used for meat and dry food grinding do not have any hydraulic problem. Generally known paper pulp grinders have the knives arranged in such a way that the pulp flows parallel to the knives, which arrangement brings about the result that a great part of the total pulp is not crushed and ground between the rotating and non-rotating knives and leaves the grinding device without having been subjected to any grinding action. As a matter of fact, disc grinding devices are known in which the pulp is supposed to pass axially through the discs. However, in said known devices, the grinding members consist of a plate on which a relatively small number of thinly scattered knives are fixed. Only a small part of the disc surface exerts any real grinding action. If the pulp is let into the rotating disc, the pulp is directed to the periphery of the disc, due to centrifugal force, and is prevented from entering the passage-openings leading to the grinding Zone. If the pulp is so let in as to pass the non-rotating disc first, the passage-openings have to be very wide, resulting in a low number of knives and a low grinding efficiency, otherwise narrow openings have the tendency to act as the mesh of a filter screen and to separate water and fibers as the pulp is not held continuously in motion.

All the drawbacks are eliminated in the devices according to the invention. The defibrating and grinding members consist exclusively of knives arranged in such a manner that the whole surface or practically the whole working surface of the grinding member participates in the most effective manner in the treatment of pulp. The through-passage openings are very narrow, just sufficient to feed the pulp to the grinding zone. Since the pulp is continuously held in motion from the pulp inlet to the pulp outlet, and since the intensity of the motion increases in the direction of the pulp outlet of the grinding device, even pulp of highest concentration can be treated without danger of fiber and water separation. The centrifugal force developed by the first rotating grinder member is fully used to force the pulp to the grinding zone and the suction developed by the next rotating grinding member leads the pulp through the intermediate non-rotating grinding member to a repeated grinding action with increased efiiciency.

The present device effects multiple-action grinding, and the efliciency increases with every added rotating grinding member in the direction from pulp inlet to pulp outlet. Compared with the first rotating grinding member, the next rotating grinding member has at least equivalent grinding area, or has a larger grinding area and rotates at the same speed or rotates at substantially different speed.

Each grinding stage has separate means for controlling the grinding pressure. This multiple-action grinding is necessary as the material to be defibrated and ground arrives always in coarse form, containing fiber bundles, pulp flakes and incompletely disintegrated wood chips. The fibers have to be separated and slightly ground in the first stage. As such coarse material covers a smaller area compared to the finely separated fibers, the grinding eflicieney has to be lower in the first grinding stage and higher in the following stage or stages.

I claim:

1. An apparatus for defibrating and grinding paper pulp or other vegetable fibrous material comprising a container having a pulp inlet and pulp outlet spaced from each other, a first rotatable grinding member, a non-rotatable dual-faced. grinding member, and a second rotatable grinding member mounted in series in said container across the passage between the pulp inlet and pulp outlet, said rotating grinding members being rotatable at different speeds, so that in the direction from pulp inlet to pulp outlet the second rotatable grinding member has a higher rotating speed compared to that of the first rotatable grinding member, separate means for rotating said rotatable grinding members, separate means for displacing the grinding members in axial direction, all of said grinding members having cooperating confronting working faces each consisting of a plurality of substantially rigid and immovable knife elements forming a knife system extending from the edge portion of each grinding member approximately to its center and having substantially radially extending openings between all the knife elements from the edge portion of each grinding member approximately to its center, so that substantially the whole area of each grindeach other, at least three defibrating and grinding meming member effectively participates in the multiple treatment of the pulp in passage from the pulp inlet to the pulp outlet of said container and each successive treatment has increased efiiciency.

2. An apparatus for defibrating and grinding paper pulp or other vegetable fibrous material comprising a container having a pulp inlet and pulp outlet spaced from each other, two axially non-duplicable rotatable grinding members and two non-rotatable grinding members mounted in said container across the passage between the pulp inlet andpulp ouflet, said rotatable grinding members having different sized working areas, so that in the direction from pulp inlet to pulp outlet the second rotatable grinding member has a larger working area and corresponding higher circumferential speed compared to the first rotatable grinding member, means for rotating said rotatable grinding members in common, said two non-rotatable grinding members being between the two rotatable grinding members and displaceable separately in axial direction, all of said grinding members having cooperating confronting Working faces each consisting of a plurality of substantially rigid and immovable knife elements forming a knife system extending from the edge portion of each grinding meniber approximately to its center and having substantially radially extending openings between all the knife elements from the edge portion of each grinding member approximately to its center, so that substantially the whole area of the grinding member effectively participates in the multiple treatment of the pulp in passage from the pulp inlet to the pulp outlet of said container and each successive treatment has increased efficiency.

3. An apparatus for defibrating and grinding paper pulp or other vegetable fibrous material comprising a container having a pulp inlet and pulp outlet spaced from each other, at least two axially non-displaceable rotatable grinding members and at least two non-rotatable grinding members mounted in said container across the passage between the pulp inlet and pulp outlet, said rotatable grinding membershaving different sized working areas, so that in the direction from pulp inlet to pulp ouflet the next rotatable grinding member in series has a larger working area compared to the preceding rotatable grinding member, means for rotating said rotatable grinding members in common, each of said non-rotatable grinding members being behind a rotatable grinding member and said non-rotatable grinding members being displaceable separately in axial direction, all of said grinding members having cooperating confronting working faces and each rotatable grinding member cooperating with one non-rotatable grinding member, each of said working faces consisting of a plurality of substantially rigid and immovable knife elements forming a knife system extending from the edge portion of each grinding member approximately to its center and having substantially radially extending openings between all Y the knife elements from the edge portion of each grinding member approximately to its center, so that substantially the whole area of the grinding member effectively bers mounted in said container across the passage between the pulp inlet and pulp outlet, at least two of said grinding members being rotatable and at least one of said grinding members beingnon-rotatable, the rotatable and non-rotatable grinding members being so positioned with respect to each other as to provide at least two grinding zones in series, the next succeeding grinding zone having a greater knife elements from the edge portion of each grinding member approximately to its center, so that substantially the whole area of the grinding member effectively participates in the multiple-treatment of the pulp in passage from the pulp inlet to the pulp outlet of said container.

5. An apparatus according to claim 4, in which the grinding members have the shape of a conical disc.

6. An apparatus according to claim 4, in which the grinding members have the shape of a plane disc.

. ,7. An apparatus according to claim 4, in which the grinding members have the shape of a hollow frustum of a cone. 7

8. An apparatus according to claim 4, in which the grinding members have the shape of a curved disc.

9. An apparatus according to claim 4, in which the knife elements are held together by connecting members which do not extend to the working face of the grinding member.

10. An apparatus according to claim 4, in which the grinding members are provided with a seal ring at the periphery closing the free space between the connecting members and the Working face of the grinding member, saidseal ring being made of softer and faster-wearing material than the knives.

11. An apparatus according to claim 4, in which the non-working face of the first'rotatable grinding member is partly closed with a seal plate adapted to prevent pulp recirculation to the pulp inlet of the container.

12. An apparatus according to claim 4, in which the pulp inlet is in the center of the container.

13. An apparatus according to claim 4, in which the pulp outlet is in the center of the container.

14. An apparatus according to claim 4, in which the knife elements have a smooth working face.

' 15. An apparatus according to claim 4, in which the knife elements have a grooved working face.

16. An apparatus according to claim 1, in which the rotatable grinding members are adapted and arranged to rotate at the same speed but in opposite directions.

References Cited in the file of this patent UNITED STATES PATENTS 2,394,182 luglis Feb. 5, 1946 2,685,826 Black Aug. 10, 1954 FOREIGN PATENTS 128,546 Germany Mar. 4, 1902 262,070 Great Britain May 19, 1927 669,988 Great Britain Apr. 9, 1952 

